Vaccination against harmful infectious diseases has been one of the most important public health advances of the last century. Due to surging demand for a wider range of vaccines, the vaccine industry is facing a challenge to update from traditional, time-consuming methods to new, more efficient approaches. Virus quantification represents a rate-limiting step at many stages of vaccine development and production, for both egg and cell culture as indicated by the stars in the schematic to the right. Currently, one of the most widely used tools for the determination of virus concentration is the viral plaque assay, or variations such as tissue/egg culture infectious dose, TCID50/EID50. The viral plaque assay is a cumbersome, subjective and traditional biological technique that was originally applied to the quantification of animal viruses in 1952. Other methods for virus quantification exist, including a variety of ELISA-type protein assays, transmission electron microscopy (TEM), and quantitative PCR (qPCR). However, each of these methods has its own drawbacks, perhaps the most important being that they require well-trained technicians and have significant time to result. The ViroCyt Virus Counter technology represents a breakthrough in virus quantification as it requires minimal training and provides a direct, physical measurement of total intact virus concentration within minutes. The ability to track virus levels in real-time, which is not possible with traditional methods, ensures an optimal harvest time with the highest yields. To learn more, email us at


“We have basically stopped running plaque assays on our P0 and P1 virus stocks because the accuracy of the titers obtained with the Virus Counter leads to better virus amplifications than those obtained using plaque assay titers. The instrument saves one to two weeks on our virus production timeline and it is very helpful to know within a day or two that a transfection or co-transfection has yielded virus particles.”



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